Sonar navigation system and method

ABSTRACT

A method for pre-determining an underwater objects GPS position using a rotatable scan sonar unit linked to a boat, magnetic compass and GPS receiver. This system determines the underwater objects GPS position using the objects distance, compass heading and a GPS receiver/sonar on a boat. This system will provide real time longitude and latitude positions of underwater objects seen with sonar at a distance from a boat, and will allow for precise autopilot navigation or fixed position fishing. The system can also be used to correct for GPS errors when using previously stored waypoints positions of an object. The computer determines an objects underwater GPS position using a sonar transducer and mounted on a 360 degree movable mechanism such as a trolling motor unit, or phased array of transducers and a compass to provide heading information and formulates the objects position based on the distance and heading of the object in relation to the boats current GPS position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/652,438, filed Oct. 15, 2012, which is acontinuation application of U.S. patent application Ser. No. 12/537,887,filed Aug. 7, 2009 entitled SONAR NAVIGATION SYSTEM AND METHOD, whichclaims priority to U.S. Provisional Application No. 61/087,098, filedAug. 7, 2008 entitled SONAR NAVIGATION SYSTEM AND METHOD, all of whichare incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to sonar navigation systems. Inparticular, the present invention relates to a system and method forstoring and/or recalling coordinates of the location of underwaterobjects.

SUMMARY OF THE INVENTION

Sonar units are an important tool for fisherman on a boat sonar unitsprovide the user water depth, structure and fish location. The sonartransducer is used to send echo signals to determine the position of anobject and the distance to the object in the water. The sonar transducercan be mounted in several different boat locations including transommount, through hull or mounted on the lower unit of an electric trollingmotor providing multi directional pointing of the sonar echo beam. Thesonar transducer can also be mounted in different configurationsincluding, side scan, forward scan, backward scan and down scan viewingof objects in many directions in the water. With the ability to scan inmultiple directions the fisherman can cast to objects in the waterwithout getting to close to scare the fish off of these objects. Theobjects in the water may be in the form of submerged trees, rocks,boats, fish cribs and many other underwater objects. Sonar units mayalso have built in GPS receivers used to show the boats position orpreviously stored GPS waypoint positions showing structure found in thelake that fish like to hide in. Some sonar units have the ability toside scan large areas of water showing objects on the bottom of thelake, and are capable of marking these objects position based upon GPSdata stored at the time of the sonar side scanning The user can freezethe sonar display screen and cursor to the previously viewed object onthe screen and mark or store the GPS position to use later fornavigation to the object. These side scan systems require the boat to bemoving to determine the compass heading using the GPS movement tocalculate the heading. There is a need for accurately determining anobject's GPS location if the boat is in a fixed position. Using acompass mechanically in line with the pointing direction of the sonarbeam allows for an improved method for determining the GPS position ofan object in the water. This sonar/compass configuration is mounted on a360-degree movable mechanism allowing for sweeping or scanning of alarge area while the boat is in a fixed position or moving.

As such, the present invention is directed towards an improved methodfor determining the GPS position of an object in the water up tohundreds of feet or more away from the boat. This is done with aid oflong range side scan sonar technology and by mounting a side/forwardscan sonar transducer to the lower unit of an electric trolling motor.The fisherman can then direct the sonar beam by slowly spinning/steeringthe trolling motor lower unit, scanning the lake bottom 360 degrees andhundreds of feet from the boat. This system works whether the boat ismoving or standing still. The sonar computer continuously stores compassheading, distance, and current GPS position as the lake bottom isscanned. The user can select any object (current or past view) on thescreen to determine the GPS position of that object and use the GPS datato navigate the boat or correct previously stored object positions as aform of GPS error correction. The system determines the GPS position ofobjects with the aid of a compass linked or inline with the sonartransducers scannmg direction and pointing device(trolling motor) thatmay be in the form of a steerable trolling motor connected to a sonarunit. The GPS position is calculated by the sonar computer knowing thedistance the object is from theboat and the compass heading directionpointing to the object. The computer then reads the boat's currentlongitude and latitude position and formulates the object's positionusing the distance and compass direction to the object. The underwaterobject GPS position data can be used for the boat's auto pilotnavigation to guide the boat to the under water object. The user can seta distance parameter keeping the boat within a set distance away fromthe object, allowing the fisherman to cast to the object but keeping afar enough distance not to scare off the fish hiding in the object. Thesystem may also incorporate a wind detection device to properly keep theboat pointing into the wind allowing for accurate boat navigation. Theforward/side scan sonar transducer may be attached to the trolling motorlower with a removable bracket or may be manufactured permanently intothe trolling motor lower unit casing.

In another embodiment, the system may incorporate sonar using a360-degree view showing the bottom of the lake all the way around theboat. This system will control the turning speed of the sonar transducerby spinning the trolling motor steering motor at a specific rotationspeed, this speed can be measured by a feedback position sensor on themotor or by using the compass heading data measuring the degree ofmovement over time. As the transducer spins the lake bottom is scannedand the image is drawn on the sonar screen. A stand-alone motorizedmechanical spinning transducer device can also be used to replace thetrolling motor as a turning mechanism. Another configuration of a 360degree scanning system my incorporate a fixed position hull mountedphase array electronic scanning transducer with compass. This systemuses the same object detection method described above to determine GPSwaypoint positions of objects around the boat using a fixed boat mountedcompass module.

In another embodiment the compass module that is mounted in the trollingmotor may be used as a direction pointer and is coupled to the sonarunit for directing the map view image on the sonar screen. This systemwill allow the user to rotate the navigation map image 360 degreesaround showing what direction (heading) the boat should go to navigateto a GPS waypoint. The waypoint may be underwater objects like trees,rocks and other submerged objects. This method will be very helpful tothe user as it will give a good visual understanding of the currentpointing position of the trolling motor head in relation to markedwaypoints and objects in the water. Current sonar units require the boatto be moving to acquire a compass heading using GPS generated headings.This system is unique, as the trolling motor pointing heading directionwill automatically control the view of the map on the sonar without theneed for the boat to be moving to acquire a compass heading.

Other aspects of the present invention will become apparent and be morefully understood from the following detailed description andaccompanying drawings, which set forth illustrative embodiments that areindicative of some of the various ways in which the principals of theinvention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the trolling motor with a compass and atransducer.

FIG. 2 is a diagram showing the transducer coupled to a motor for 360degree positioning.

FIG. 3 is a block diagram of the sonar system.

FIG. 4 is a diagram showing various sonar display views.

DETAILED DESCRIPTION

The description that follows describes, illustrates and exemplifies oneor more particular embodiments of the present invention in accordancewith its principles. This description is not provided to limit theinvention to the embodiments described herein, but rather to explain andteach the principles of the invention in such a way to enable one ofordinary skill in the art to understand these principles and, with thatunderstanding, be able to apply them to practice not only theembodiments described herein, but also other embodiments that may cometo mind in accordance with these principles. The scope of the presentinvention is intended to cover all such embodiments that may fall withinthe scope of the appended claims, either literally or under the doctrineof equivalents.

FIG. 1 shows an electric trolling motor 1 equipped with a compass module2 built into the top of the motor head. The lower unit 2 a has a fourdirectional sonar transducers 3, 6 at the front of the lower unit. Thetransducers can send sonar beams forward, backward and the left andright to the sides. The compass 2 is in line with the transducerallowing the system tomeasure the heading direction of the sonar beams.This is significant in detecting the underwater objects position inrelation to the trolling motors pointing direction. This distance andheading are significant in calculating the GPS position of the object inthe water. Steering motor 4 is used to tum the motor and sweep thewaters around the boat searching for objects like submerged structure,weeds, trees, rocks, cribs, weed lines and fish.

FIG. 2 is a stand alone steering device using steering motor 7 to directthe sonar transducers 3, 6 in the desired direction scanning forunderwater objects. Compass 5 is used to know the heading an object islocated at. This device can be a stand alone pointing unit that may bemounted directly to the bottom of the boat. This eliminates the need foran electric trolling motor to position the sonar scanning beam.

FIG. 3 is a block diagram showing the trolling motor transducer 20,compass 21, and steering motor 23 connected to the sonar computer system19. The pointing direction of the trolling motor can be controlled bythe sonar computer via steering control 24 and can be used to provide360 degree circle scanning or can be controlled by an external wirelessremote control steering device 27. This external steering remote mayalso have a slow speed steering option to allow for variable speedturning of the trolling motor, to sweep the lake bottom in detail. Sonartransducer 20 is mechanically linked and in line with the compass module21 with trolling motor 22. The compass data is passed to the sonarcomputer 19 and provides heading data used to formulate the GPSlongitude and latitude of an object seen in the water by the sonar. Thetransducer 20 transmits sonar echoes in the water allowing the sonarcomputer 19 to create an image on the display that represents the lakebottom. The sonar computer also stores compass heading, GPS position anddistance information along with the sonar images. This information canbe used later to mark a waypoint location of an object. The user canselect objects on the sonar display 25 via a cursor or touch displayLCD. Once an object or location is selected on the display, the computer19 uses the previously stored information to generate the selectedobjects GPS waypoint position. To formulate the GPS longitude andlatitude of a selected point, location or object, the computer uses thecurrent or stored position of the boat via the GPS receiver 19 a and theheading/pointing direction of the sonar beam, with the distance to thatlocation/object toformulate the desired GPS longitude and latitude.

One example of a set of formulas that may be useful to generate thedesired latitude and longitude coordinates for this position is setforth below. These formulas also take into account the earth'scircumference, although this is not necessary for short distances usedwith this system, as follows:

lat asin(sin(lat 1)*cos(d)+cos(lat 1)*sin(d)*cos(tc))

dlon atan2(sin(tc)*sin(d)*cos(lat1),cos(d)−sin(lat 1)*sin(lat))

Ion mod(lon1−dlon+pi,2*pi)−pi

Where a angle; lat 1/lon 1 current position; d distance; tccircumference.

Sonar computer 19 can be programmed using C or Assembly languagesoftware to process this formula, and can also use a RISC stylemicroprocessor, such as can be provided by MICROCHIP (Chandler, Ariz.)Eighteen (18) series microprocessor. The computer 19 can also use thenewly formulated GPS position of an object to correct for GPS errorsknowing that a previously marked waypoint is being viewed near thisposition. The user can correct the position of the previously storedwaypoint by highlighting the old waypoint and pressing a correctionbutton on the sonar control module 26. The user could also use thisreference object to correct all waypoints stored on the lake. Sonardisplay 25 provides images of underwater objects along with navigationalmap views. The control buttons 26 are used to program and operate thesonar system. The trolling motor seen in FIG. 3 also provides the user aview of an object while navigated towards that object. This can beaccomplished when using a forward scan transducer in conjunction withthe compass and autopilot navigation system. This navigation systemallows the sonar unit to control the navigation by reading the compassheading 12 from the trolling motor 22 and controlling the steering viathe trolling motor steering control 24. The user can also offset thecompass 12 positions to help view the object while navigating toward it.The offsetting of the compass can be manually done via a remote controldevice 27 or can be offset using the sonar controls 26.

The sonar system seen in FIG. 3 is also capable of keeping the boat at aspecified distance from the boat. The user can select how many feet theywould like the boat to be away from an object and the GPS navigationsystem will keep the boat within that distance. This will be usefulwhile fishing as the fisherman may want to stay away from an object tokeep from chasing the fish away do to the fisherman's presents.

FIG. 4 diagram shows the display views of the sonar unit 25. Displayview 8 shows a forward scan image of the boat 9 scanning the water up to200 feet. An object 10 can be seen 100 feet away from the boat 11. Thisobject is located 180 degrees in line with the head of the trollingmotor unit compass 2. This display view may be used to select anydirection of the trolling motor (forward, backward or left and rightside scan). In anyone of these views the compass 21 can provide thedirection of an object in the water. The display may also providemultiple views with split view mode. Display view 13 shows a map styleimage of the lake and position of the boat 14 in relation to the objects15, 16, 17, in the water. Because the compass 21 is connected to thesonar computer 19, the view of the map in relation to the boat will betrue to the pointing position of the trolling motor head pointingdirection. This is significant as the user may want to direct the boatto a previously stored waypoint or object and can do so by simplyturning the trolling motor head into the direction of the object seen onthe display. The sonar display has the option to reposition the boat'sicon position or tum the complete display image so the pointingdirection can be seen at the top of the display. This means the displaywill rotate in relation to the pointed position. Most sonars use a GPSgenerated compass heading that does not operate when the boat isstanding still and the boat's or trolling motor's pointing position doesnot match the image on the screen. That is only one of the benefits ofhaving a compass mounted in the trolling motor head and connected to thesonar GPS system.

Sonar image 18 shows a 360 degree image of the bottom of the lake aroundthe boat. This image is drawn by the sonar precisely spinning thetransducer slowly around and creating an image. The compass heading canbe used to set the turning speed of the transducer assembly by measuringthe amount of movement in degrees over time. As the motor turns and theimage is created, the compass heading and GPS position of the boat isstored allowing for object position selecting when the scan is complete.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. Accordingly, theparticular arrangements disclosed are meant to be illustrative only andnot limiting as to the scope of the invention which is to be given thefull breadth of the appended claims and any equivalent thereof.

What is claimed is:
 1. A sonar navigation system comprising: a processorconfigured to draw a sonar image in response to sonar informationreceived from a sonar transducer mounted on a rotatable member forscanning an underwater area, the sonar image comprising a plurality ofunderwater objects identified by the sonar information, wherein thesonar transducer generates the sonar information as the rotatable membersweeps the sonar transducer over an angular distance; and a displayscreen communicatively coupled to the processor and configured todisplay the sonar image in response to the processor drawing the sonarimage.
 2. The system of claim 1 wherein the angular distance is a 360degree circle and the sonar image is a 360 degree image.
 3. The systemof claim 1 wherein the angular distance is an arc of up to 360 degrees.4. The system of claim 1 wherein the angular distance is a preset valueup to 360 degrees and the processor is further configured to cause therotatable member to rotate over the preset value.
 5. The system of claim1 wherein the processor is further configured to determine a set oflocation coordinates for at least one of the plurality of underwaterobjects based on the sonar information, wherein the sonar informationfurther includes a distance between at least one of the plurality ofunderwater objects and the sonar transducer.
 6. The system of claim 5wherein the processor is configured to determine the set of locationcoordinates based further on a direction heading received from a compasspositioned in-line with a pointing direction of the sonar transducer anda current position of the sonar transducer received from a positiondetection receiver.
 7. The system of claim 1 wherein the rotatablemember is selected from a group consisting of a motorized device and atrolling motor.
 8. The system of claim 1 wherein the rotatable member isa trolling motor and the sonar transducer is mounted to a lower unit ofthe trolling motor.
 9. A sonar system comprising: at least one sonartransducer configured to transmit a sonar beam for scanning anunderwater area and to generate sonar information identifying one ormore underwater objects in the underwater area; and a rotatable membercoupled to the at least one sonar transducer and configured to sweep theat least one sonar transducer over an angular distance.
 10. The systemof claim 9, further comprising a processor configured to draw a sonarimage of the one or more underwater objects in response to sweeping theat least one sonar transducer over the angular distance, the sonar imagebeing based on the sonar information.
 11. The system of claim 10 whereinthe angular distance is a 360 degree circle and the sonar image is a 360degree image.
 12. The system of claim 10 further comprising a displayscreen configured to display the sonar image.
 13. The system of claim 10wherein the processor is further configured to control rotation of therotatable member over the angular distance and the angular distance is apreset value up to 360 degrees.
 14. The system of claim 10 wherein theprocessor is further configured to control transmission of the sonarbeam by the at least one sonar transducer.
 15. The system of claim 10wherein the processor is further configured to determine locationcoordinates for the one or more underwater objects based on the sonarinformation, a direction heading of the at least one sonar transducer,and a current position of the at least one sonar transducer, the sonarinformation including a distance to the one or more underwater objects.16. The system of claim 15 further comprising a compass positionedin-line with a pointing direction of the at least one sonar transducer,the compass being configured to determine the direction heading.
 17. Thesystem of claim 15 further comprising a position detection receiverconfigured to determine the current position of the at least one sonartransducer.
 18. The system of claim 9 wherein the at least one sonartransducer includes two sonar transducers, each sonar transducertransmitting a separate sonar beam.
 19. The system of claim 9 whereinthe angular distance is an arc of up to 360 degrees.
 20. The system ofclaim 9 wherein the rotatable member is selected from a group consistingof a motorized device and a trolling motor.
 21. The system of claim 9wherein the rotatable member is a trolling motor and the at least onesonar transducer is mounted to a lower unit of the trolling motor.